• Journal of Korean Home Economics Education Association
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• v.30 no.4
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• pp.141-164
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• 2018

The purpose of this study was to investigate the stress perception, dietary habits, lifestyle and snack intake behaviors of students to help dietary education of high school students in Jeonnam area. The data were collected from high school students in Jeonnam area and 503 questionnaires were used for analysis. The main results of this study are as follows. First, the mean scores of high school students' perception of stress were 2.92 points for male students and 3.07 points for female students, and female students were statistically significantly higher than male students(p<.01). Stress perceptions showed significant differences in school stress(p<.001) and family stress(p<.05) according to gender, and female students gained more stressed than male students. Second, the dietary habits and lifestyle characteristics of high school students by gender showed significant difference between male students and female students at the one meal time(p<.001), the amount of meal(p<.05), the tendency of eating habits(p<.001), the salty taste of food(p<.05), the exercise frequency per week(p<.001) and the exercise time per day(p<.001), respectively. One meal time was shorter for male students than for female students, and the amount of meals was more suitable amount for female students than male students. Also, male students ate more regularly than female students and female students preferred more stimulating foods than male students. Male students ate slightly bland salty taste, and female students ate standard salty taste. The exercise frequency per week and the exercise time per day were more in male students than in female students. Third, the snack intake characteristics of high school students by gender showed significantly different between male students and female students at the cost of snack per day(p<.01), the time to eat snacks(p<.01) and the favorite snacks(p<.001), respectively. The cost of snack per day was higher for female students than for male students in case of less than 4,000 won. The time for eating snack showed that 'Irregularly' was high for male students and 'In the evening after lunch' was high for female students. The favorite snacks were cookies, candies and chocolates for male and female students. Forth, the dietary habits and lifestyle characteristics of high school students by stress level showed significantly different at the frequency of daily meals(p<.05), the tendency of eating habits(p<.01) and the salty taste of food(p<.05), respectively. The frequency of daily meals was more than four times in case of the 'High stress' and 'Low stress' groups. The tendency of eating habit was low in regular meal rate in 'High stress' group. Fifth, the snack intake characteristics of high school students by stress level showed significantly different in the frequency of snacks per day(p<.05) and the favorite taste of snacks(p<.05). In case of the frequency of daily snack intake, 'More than 4 times' was highest in 'High stress' group and 'Low stress' group. The favorite taste of snacks showed that the spicy taste was highest in the 'High stress' group and the 'Low stress' group.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.465-478
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• 1995

The objective of this study was to investigate the impacts of large-scale timber harvesting on the environment of a mature hardwood forest. To achieve the objective, the effects of harvesting on forest environmental factors were analyzed quantitatively using the field data measured in the study sites of Seoul National University Research Forests [(Mt.) Paekunsan] for two years(1993-1994) following timber harvesting. The field data include information on vegetation, soil mesofauna, physicochemical characteristics of soil, surface water runoff, water quality in the stream, and hillslope erosion. For comparison, field data for each environmental factor were collected in forest areas disturbed by logging and undisturbed, separately. The results of this study were as follows : The diversity of vegetational species increased in the harvested sites. However, the similarity index value of species between harvested and non-harvested sites was close to each other. Soil bulk density and soil hardness were increased after timber harvesting, respectively. The level of organic matter, total-N, avail $P_2O_5$, CEC($K^+$, $Na^+$, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$) in the harvested area were found decreased. While the population of Colembola spp., and Acari spp. among soil mesofauna in harvested sites increased by two to seven times compared to those of non-harvested sites during the first year, the rates of increment decreased in the second year. However, those members of soil mesofauna in harvested sites were still higher than those of non-harvested sites in the second year. The results of statistical analysis using the stepwise regression method indicated that the diversity of soil mesofauna were significantly affected by soil moisture, soil bulk density, $Mg^{{+}{+}}$, CEC, and soil temperature at soil depth of 5(0~10)cm in the order of importance. The amount of surface water runoff on harvested sites was larger than that of non-harvested sites by 28% in the first year and 24.5% in the second year after timber harvesting. The level of BOD, COD, and pH in the stream water on the harvested sites reached at the level of the domestic use for drinking in the first and second year after timber harvesting. Such heavy metals as Cd, Pb, Cu, and organic P were not found. Moreover, the level of eight factors of domestic use for drinking water designated by the Ministry of Health and Welfare of Korea were within the level of the first class in the quality of drinking water standard. The study also showed that the amount of hillslope erosion in harvested sites was 4.77 ton/ha/yr in the first year after timber harvesting. In the second year, the amount decreased rapidly to 1.0 ton/ha/yr. The impact of logging on hillslope erosion in the harvested sites was larger than that in non-harvested sites by seven times in the first year and two times in the second year. The above results indicate that the large-scale timber harvesting cause significant changes in the environmental factors. However, the results are based on only two-year field observation. We should take more field observation and analyses to increase understandings on the impacts of timber harvesting on environmental changes. With the understandings, we might be able to improve the technology of timber harvesting operations to reduce the environmental impacts of large-scale timber harvesting.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.2
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• pp.115-127
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• 2020

The Unsang gold deposit has been one of the three largest deposits (Daeyudong and Kwangyang) in Korea. The deposit consists of Au-bearing quartz veins filling fractures along fault zones in Precambrian metasedimentary rock and Jurassic Porphyritic granite, which suggests that it might be an orogenic-type. Based on its mineral assemblages and quartz textures, quartz veins are classified into 1)galena-quartz, 2)pyrrhotite-quartz, 3)pyrite-quartz, 4)pegmatic quartz, 5)muscovite-quartz, and 6)simple quartz vein types. The pyrite-quartz vein type we studied shows the following alteration features: sericitization, chloritization, and silicification. The quartz vein contains minerals including white quartz, white mica, chlorite, pyrite, rutile, calcite, monazite, zircon, and apatite. Rutile with euhedral or medium aggregate occur at mafic part from laminated quartz vein. Two types of rutile are distinguishable in BSE image, light rutile is texturally later than dark rutile. Chemical composition of rutile has 89.69~98.71 wt.% (TiO₂), 0.25~7.04 wt.% (WO₃), 0.30~2.56 wt.% (FeO), 0.00~1.71 wt.% (Nb₂O₅), 0.17~0.35 wt.% (HfO₂), 0.00~0.30 wt.% (V₂O₃), 0.00~0.35 wt.% (Cr₂O₃) and 0.04~0.25 wt.% (Al₂O₃), and light rutile are higher WO₃, Nb₂O₅ and FeO compared to the dark rutile. It indicates that dark rutile and light rutile were formed at different stage. The substitution mechanisms of dark rutile and light rutile are suggested as followed : dark rutile [(V³⁺, Cr³⁺) + (Nb⁵⁺, Sb⁵⁺) ↔ 2Ti⁴⁺, 4Cr³⁺ (or 2W⁶⁺) ↔ 3Ti⁴⁺ (W⁶⁺ ↔ 2Cr³⁺), V⁴⁺ ↔ Ti⁴⁺], light rutile [2Fe³⁺ + W⁶⁺ ↔ 3Ti⁴⁺, 3Fe²⁺ + W⁶⁺ ↔ Ti⁴⁺ + (V³⁺, Al³⁺, Cr³⁺) +Nb⁵⁺], respectively. While the dark rutile was formed by cations including V³⁺, V⁴⁺, Cr³⁺, Nb⁵⁺, Sb⁵⁺ and W⁶⁺ by regional metamorphism of hostrock, the postdating light rutile was formed by redistribution of cations from predating dark rutile and addition of Fe²⁺ and W⁶⁺ from Au-bearing hydrothermal fluid during ductile shear.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.273-288
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• 2023

The Gubong Au-Ag deposit, which has been one of the largest deposits (Unsan, Daeyudong, Kwangyang) in Korea, consists of eight lens-shaped quartz veins (a mix of orogenic-type and intrusion-related types) that filled fractures along fault zones within Precambrian metasedimentary rock. Korea Mining Promotion Corporation found a quartz vein (referred to as the No. 6 vein with a grade of 27.9 g/t Au and a width of 0.9 m) at a depth of -728 ML by drilling (No. 90-12) conducted in 1989. Korea Mining Promotion Corporation conducted drilling (No. 04-1) in 2004 to investigate the redevelopment's possibility of the No. 6 vein. The author studied the occurrence and chemical composition of chlorite and white mica using wallrock, wallrock alteration and quartz vein samples collected from the No. 04-1 drilling core in 2004. The alteration of studied samples occurs chloritization, sericitization, silicification and pyritization. Chlorite and white mica from mineralized zone at a depth of -275 ML occur with quartz, K-feldspar, calcite, rutile and pyrite in wallrock alteration zone and quartz vein. Chlorite and white mica from ore vein (No. 6 vein) at a depth of -779 ML occur with quartz, calcite, apatite, zircon, rutile, ilmenite, pyrrhotite and pyrite in wallrock alteration zone and quartz vein. Chlorite from a depth of -779 ML has a higher content of Al and Mg elements and a lower content of Si and Fe elements than chlorite from a depth of -275 ML. Also, Chlorites from a depth of -275 ML and -779 ML have higher content of Si element than theoretical chlorite. Compositional variation in chlorite from a depth of -275 ML was mainly caused by phengitic or Tschermark substitution [Al^{3+,VI + Al3+,IV} <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], but compositional variation from a depth of -779 ML was mainly caused by octahedral Fe²⁺ <-> Mg²⁺ (Mn²⁺) substitution. The interlayer cation site occupancy (K+Na+Ca+Ba+Sr = 0.76~0.82 apfu, 0.72~0.91 apfu) of white mica from a depth of -275 ML and -779 ML have lower contents than theoretical dioctahedral micas, but octahedral site occupancy (Fe+Mg+Mn+Ti+Cr+V+Ni = 2.09~2.13 apfu, 2.06~2.14 apfu) have higher contents than theoretical dioctahedral micas. Compositional variation in white mica from a depth of -275 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], illitic substitution and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution. But, compositional variation in white mica from a depth of -779 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV] and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution.

• Journal of Korean Society of Forest Science
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• v.52 no.1
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• pp.37-49
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• 1981

The purpose of the study is to find out the objective method of valuation on the forest stands through the analysis of logging costs that is positively related to timber production. The two forest (Amgog, Whangryoung), located nereby, but forest type, logging and skidding conditions being slightly different, were slected to carry out the study. The objective timber stumpage value were determined by investigating the appropriate timber production costs and profits of logging operations. The main result obtained in this study are as follows: 1. The rate of logging cost in consisting of timber market price is 13.15% in the area of Amgog logging place and 19.48% in Whangryoung. 2. The rate of the other production cost excluding logging cost is 15.36% in the area of Amgog logging place and 28.85% in Whangryoung. 3. The total rate of timber production cost in consisting of the market price is more than 28.51% in the area of Amgog logging place and 48.33% in Whangryoung, 4. Though the productivity of forest land is affected by the selection of tree species, tending, treatments and effective management of forest land, the more important problem is improvement of logging condition. 5. The rate of production cost in timber price is so high that we should endeavore to improve the productivity of labour and its quality, and minimize the difference of piece work per day in accordance to the various site condition. 6. Although the profit of forest industry is related to the period of recapturing investment, it is more closely related to the working condition, risk of investment and continuous change of social investment interest. 7. If the right variables which are related to the timber market, are objectively obtained, the stumpage value of mature forests can be objectively caculated by applying straight line discounting method or compound discounting method in caculating the stump to market price.